Abstract: A hot-deformed magnet is obtained by quenching and solidifying a melt of an alloy containing a rare earth element (RE), Fe, and B as main components by a super quenching method using a rotating roll; preparing an alloy powder in an amorphous structure state or an amorphous-microcrystalline mixed structure state; subjecting the alloy powder to a rapid heat treatment in a falling-type heating furnace so as to obtain a raw material powder; hot-forming the raw material powder so as to densify the raw material powder to near true density and form a hot-formed compact; and subjecting the hot-formed compact to uniaxial hot plastic working to orient crystals.

Abstract: A problem of the present invention is to prevent a magnetic property from degrading and suppress eddy currents efficiently. A motor permanent-magnet (1) according to the present invention includes a coating film (12) near a surface where an eddy current tends to flow in a great magnitude. The eddy current is cut off by an electrical nonconductive a matrix (13) intervening between magnetic phases (14) as well as small dispersed eddy currents flow in respective magnetic phases (14). In this motor permanent-magnet (1), the coating film (12) suppresses the eddy currents, which originally become great in magnitude near the surface, to make the eddy current small.

Abstract: There is provided a rare-earth permanent magnet optimized to an IPM type motor for a car, capable of improving corrosion resistance, abrasion resistance, and impact resistance. The rare-earth permanent magnet 16 is configured by forming an electroplated Ni coating film 21, of which thickness is 15 ?m or more and 30 ?m or less and of which shape is a columnar crystal structure, on a surface of a R—Fe—B system permanent magnet (R is a rare-earth element) 22. The electroplated Ni coating film 21 has a high hardness region, where the Vickers hardness is 300 or more and 600 or less, and a low hardness region, where the Vickers hardness is 150 or more and 300 or less. The rare-earth permanent magnet 16 is used in a state where the rare-earth permanent magnet 16 is inserted into a slot of a yoke in a rotor of an IPM type motor for a car.

Abstract: [Problem] To provide a process for producing a permanent magnet for use in an automotive IPM motor, which excels in all of corrosion resistance, abrasion resistance, and impact resistance. [Means for Resolution] The production process characterized in that it comprises forming on the surface of an R—Fe—B based permanent magnet a 3 to 15 ?m thick Ni film as a first layer by electroplating method, followed by a 3 to 15 ?m thick Cu or Sn film as a second layer by electroplating method, and a 4 to 7 ?m thick Ni—P alloy film as a third layer by electroless plating method, provided that the third layer has a Vicker's hardness of 2.5 to 4.5 with respect to the Vicker's hardness of the Cu or Sn electroplated film provided as the second layer taken as 1.